Charge ordering in theta-(BEDT-TTF)_2 X materials

We investigate theoretically charge ordered states on the anisotropic triangular lattice characteristic of the theta-(BEDT-TTF)_2 X materials. Using exact diagonalization studies, we establish that the charge order (CO) pattern corresponds to a ``horizontal'' stripe structure, with ...1100... CO along the two directions with larger electron hopping (p-directions), and ...1010... CO along the third direction (c-direction). The CO is accompanied by co-operative bond dimerizations along all three directions in the highest spin state. In the lowest spin state bonds along the p-directions are tetramerized. Our theory explains the occurence of a charge-induced high temperature transition as well as a spin gap transition at lower temperature.Comment: 4 pages, 4 eps figures, uses jpsj2.cl

The specificity and patterns of staining in human cells and tissues of p16INK4a antibodies demonstrate variant antigen binding

The validity of the identification and classification of human cancer using antibodies to detect biomarker proteins depends upon antibody specificity. Antibodies that bind to the tumour-suppressor protein p16INK4a are widely used for cancer diagnosis and research. In this study we examined the specificity of four commercially available anti-p16INK4a antibodies in four immunological applications. The antibodies H-156 and JC8 detected the same 16 kDa protein in western blot and immunoprecipitation tests, whereas the antibody F-12 did not detect any protein in western blot analysis or capture a protein that could be recognised by the H-156 antibody. In immunocytochemistry tests, the antibodies JC8 and H-156 detected a predominately cytoplasmic localised antigen, whose signal was depleted in p16INK4a siRNA experiments. F-12, in contrast, detected a predominately nuclear located antigen and there was no noticeable reduction in this signal after siRNA knockdown. Furthermore in immunohistochemistry tests, F-12 generated a different pattern of staining compared to the JC8 and E6H4 antibodies. These results demonstrate that three out of four commercially available p16INK4a antibodies are specific to, and indicate a mainly cytoplasmic localisation for, the p16INK4a protein. The F-12 antibody, which has been widely used in previous studies, gave different results to the other antibodies and did not demonstrate specificity to human p16INK4a. This work emphasizes the importance of the validation of commercial antibodies, aside to the previously reported use, for the full verification of immunoreaction specificity

The spatial and temporal patterns of falciparum and vivax malaria in Perú: 1994–2006

<p>Abstract</p> <p>Background</p> <p>Malaria is the direct cause of approximately one million deaths worldwide each year, though it is both preventable and curable. Increasing the understanding of the transmission dynamics of falciparum and vivax malaria and their relationship could suggest improvements for malaria control efforts. Here the weekly number of malaria cases due to <it>Plasmodium falciparum </it>(1994–2006) and <it>Plasmodium vivax </it>(1999–2006) in Perú at different spatial scales in conjunction with associated demographic, geographic and climatological data are analysed.</p> <p>Methods</p> <p>Malaria periodicity patterns were analysed through wavelet spectral analysis, studied patterns of persistence as a function of community size and assessed spatial heterogeneity via the Lorenz curve and the summary Gini index.</p> <p>Results</p> <p>Wavelet time series analyses identified annual cycles in the incidence of both malaria species as the dominant pattern. However, significant spatial heterogeneity was observed across jungle, mountain and coastal regions with slightly higher levels of spatial heterogeneity for <it>P. vivax </it>than <it>P. falciparum</it>. While the incidence of <it>P. falciparum </it>has been declining in recent years across geographic regions, <it>P. vivax </it>incidence has remained relatively steady in jungle and mountain regions with a slight decline in coastal regions. Factors that may be contributing to this decline are discussed. The time series of both malaria species were significantly synchronized in coastal (ρ = 0.9, P < 0.0001) and jungle regions (ρ = 0.76, P < 0.0001) but not in mountain regions. Community size was significantly associated with malaria persistence due to both species in jungle regions, but not in coastal and mountain regions.</p> <p>Conclusion</p> <p>Overall, findings highlight the importance of highly refined spatial and temporal data on malaria incidence together with demographic and geographic information in improving the understanding of malaria persistence patterns associated with multiple malaria species in human populations, impact of interventions, detection of heterogeneity and generation of hypotheses.</p

Population dynamics of a pathogen: the conundrum of vivax malaria

Building a mathematical model of population dynamics of pathogens within their host involves considerations of factors similar to those in ecology, as pathogens can prey on cells in the host. But within the multicellular host, attacked cell types are integrated with other cellular systems, which in turn intervene in the infection. For example, immune responses attempt to sense and then eliminate or contain pathogens, and homeostatic mechanisms try to compensate for cell loss. This review focuses on modeling applied to malarias, diseases caused by single-cell eukaryote parasites that infect red blood cells, with special concern given to vivax malaria, a disease often thought to be benign (if sometimes incapacitating) because the parasite only attacks a small proportion of red blood cells, the very youngest ones. However, I will use mathematical modeling to argue that depletion of this pool of red blood cells can be disastrous to the host if growth of the parasite is not vigorously check by host immune responses. Also, modeling can elucidate aspects of new field observations that indicate that vivax malaria is more dangerous than previously thought

Social entrepreneurs in challenging places: A Delphi study of experiences and perspectives

Social Enterprises have grown in number and scope in response to reductions in state-provided welfare and increasing ambition to improve social conditions. While a range of issues have been identified in the literature as affecting the ability of Social Enterprises to successfully conduct their activities, there is currently a dearth of research into the relative influence of these factors. This study explores and ranks the challenges faced by social entrepreneurs in South Wales. Based on a Delphi study with 21 social entrepreneurs, government policy-developers and scholars, it presents a hierarchy of 14 factors, useful instruments for informing social entrepreneurs and policy-makers about the way social enterprises are managed, and how national and local policy should be developed. As part of this, the study also identifies four novel factors that affect the sustainability of social enterprises: ‘Professionalisation of Marketing’, ‘Perception of Validity’, ‘Leadership’ and ‘Situatedness’

Host Control of Malaria Infections: Constraints on Immune and Erythropoeitic Response Kinetics

The two main agents of human malaria, Plasmodium vivax and Plasmodium falciparum, can induce severe anemia and provoke strong, complex immune reactions. Which dynamical behaviors of host immune and erythropoietic responses would foster control of infection, and which would lead to runaway parasitemia and/or severe anemia? To answer these questions, we developed differential equation models of interacting parasite and red blood cell (RBC) populations modulated by host immune and erythropoietic responses. The model immune responses incorporate both a rapidly responding innate component and a slower-responding, long-term antibody component, with several parasite developmental stages considered as targets for each type of immune response. We found that simulated infections with the highest parasitemia tended to be those with ineffective innate immunity even if antibodies were present. We also compared infections with dyserythropoiesis (reduced RBC production during infection) to those with compensatory erythropoiesis (boosted RBC production) or a fixed basal RBC production rate. Dyserythropoiesis tended to reduce parasitemia slightly but at a cost to the host of aggravating anemia. On the other hand, compensatory erythropoiesis tended to reduce the severity of anemia but with enhanced parasitemia if the innate response was ineffective. For both parasite species, sharp transitions between the schizont and the merozoite stages of development (i.e., with standard deviation in intra-RBC development time ≤2.4 h) were associated with lower parasitemia and less severe anemia. Thus tight synchronization in asexual parasite development might help control parasitemia. Finally, our simulations suggest that P. vivax can induce severe anemia as readily as P. falciparum for the same type of immune response, though P. vivax attacks a much smaller subset of RBCs. Since most P. vivax infections are nonlethal (if debilitating) clinically, this suggests that P. falciparum adaptations for countering or evading immune responses are more effective than those of P. vivax

Evolution of the mammalian lysozyme gene family

<p>Abstract</p> <p>Background</p> <p>Lysozyme <it>c </it>(chicken-type lysozyme) has an important role in host defense, and has been extensively studied as a model in molecular biology, enzymology, protein chemistry, and crystallography. Traditionally, lysozyme <it>c </it>has been considered to be part of a small family that includes genes for two other proteins, lactalbumin, which is found only in mammals, and calcium-binding lysozyme, which is found in only a few species of birds and mammals. More recently, additional testes-expressed members of this family have been identified in human and mouse, suggesting that the mammalian lysozyme gene family is larger than previously known.</p> <p>Results</p> <p>Here we characterize the extent and diversity of the lysozyme gene family in the genomes of phylogenetically diverse mammals, and show that this family contains at least eight different genes that likely duplicated prior to the diversification of extant mammals. These duplicated genes have largely been maintained, both in intron-exon structure and in genomic context, throughout mammalian evolution.</p> <p>Conclusions</p> <p>The mammalian lysozyme gene family is much larger than previously appreciated and consists of at least eight distinct genes scattered around the genome. Since the lysozyme <it>c </it>and lactalbumin proteins have acquired very different functions during evolution, it is likely that many of the other members of the lysozyme-like family will also have diverse and unexpected biological properties.</p

Solar Radiation and Tidal Exposure as Environmental Drivers of Enhalus acoroides Dominated Seagrass Meadows

There is strong evidence of a global long-term decline in seagrass meadows that is widely attributed to anthropogenic activity. Yet in many regions, attributing these changes to actual activities is difficult, as there exists limited understanding of the natural processes that can influence these valuable ecosystem service providers. Being able to separate natural from anthropogenic causes of seagrass change is important for developing strategies that effectively mitigate and manage anthropogenic impacts on seagrass, and promote coastal ecosystems resilient to future environmental change. The present study investigated the influence of environmental and climate related factors on seagrass biomass in a large ≈250 ha meadow in tropical north east Australia. Annual monitoring of the intertidal Enhalus acoroides (L.f.) Royle seagrass meadow over eleven years revealed a declining trend in above-ground biomass (54% significant overall reduction from 2000 to 2010). Partial Least Squares Regression found this reduction to be significantly and negatively correlated with tidal exposure, and significantly and negatively correlated with the amount of solar radiation. This study documents how natural long-term tidal variability can influence long-term seagrass dynamics. Exposure to desiccation, high UV, and daytime temperature regimes are discussed as the likely mechanisms for the action of these factors in causing this decline. The results emphasise the importance of understanding and assessing natural environmentally-driven change when interpreting the results of seagrass monitoring programs